Stainless Steel Welding Methods include several welding techniques to weld stainless steel. The activity requires certain parameters to be set keeping in mind the properties of the metal. Stainless steel is a popular material for welding because of its durability, corrosion resistance, and aesthetic appeal. Stainless Steel can be welded using different welding methods. They are Gas Tungsten Arc Welding, Shielded Metal Arc Welding, Gas Metal Arc Welding, Plasma Arc Welding, Submerged Arc Welding, Flux Cored Arc Welding, Electric Resistance Welding, and Laser Welding. But the most common stainless steel welding methods are MIG, TIG, and Resistance Welding. In this article, we will discuss various welding aspects of stainless steel.
- What is Stainless Steel Welding?
- Stainless Steel Welding Machines
- Stainless Steel Welding Parameters
- Stainless Steel Welding Equipment
- Stainless Steel Welding Electrodes
- Stainless Steel Welding Types
- TIG Welding Tips on Stainless Steel
- Stainless Steel Welding Standards
- Stainless Steel Welding Schools
- Stainless Steel Welding Certification
- Stainless Steel Welding Defects
- Stainless Steel Welding Tips
- Weldability of Stainless Steel
- Stainless Steel Welding Employment Areas
- Stainless Steel Welding Jobs
- Stainless Steel Welding Salary
- Stainless Steel Welding Safety
What is Stainless Steel Welding?
Stainless steel welding is a process of joining two or more pieces of stainless steel together. This is done by applying heat and pressure by using various stainless steel welding methods, such as gas tungsten arc welding (TIG), gas metal arc welding (MIG), and flux-cored arc welding (FCAW).
The stainless steel welding process is not much different from that required in welding standard carbon steel. Welders need to exercise more control and care in heating and cooling stainless steel. Before welding, the surfaces of the stainless-steel pieces must be properly cleaned and prepared to ensure a strong bond. It is noteworthy to properly match filler metals with the material being welded.
Stainless Steel Welding Machines
The most common types of stainless-steel welding machines are as follows.
1. TIG Welding Machine – GTAW welding machine uses a tungsten electrode to heat the metal. Then, it creates a molten pool and fused it together.
2. MIG Welding Machine – GMAW welding machine uses a spool of wire that is fed through the machine and melted to create the weld.
3. FCAW Machine – This welding machine uses a special type of wire that has a flux core. It produces a shielding gas that protects the weld from contaminants.
4. Resistance Spot Welding Machine – This welding machine uses electrical resistance to heat and joins the metal together.
5. Laser Welding Machine – This type of welding machine uses a high-powered laser beam to create a weld between the two pieces of metal.
6. Plasma Arc Welding Machine – PAW welding machine uses a high-velocity plasma jet to heat and fuse the metal.
7. Electroslag Welding Machine – ESW welding machine uses a consumable electrode and a slag pool to create the weld.
Stainless Steel Welding Parameters
This depends on the stainless steel welding methods being used, material thickness, and the specific grade of stainless steel. Some of the common parameters are as follows.
1. Welding Process – Different welding processes can be used for welding stainless steel including GTAW, GMAW, FCAW, etc. The choice of the welding process depends on the thickness of the material and the specific application.
2. Filler Metal – Not all welding processes require filler metal, except some. This depends on the specific grade of stainless steel and the welding process being used.
3. Shielding Gas – Argon or a mixture of argon and helium works as shielding gas for stainless steel welding. This protects the weld from oxidation and contamination.
4. Welding Current – Being an important parameter, it determines the amount of heat that is generated during welding. The current level depends on the type of welding process and the thickness of the material being used.
5. Welding Voltage – Another important parameter is welding voltage. This determines the heat input and penetration of the weld. The type of welding process and the thickness of the material decide the level of voltage.
6. Welding Speed – This is the rate at which the welding process moves along the joint. It should be adjusted to ensure proper penetration and fusion.
7. Preheat/Post-weld Heat Treatment – This parameter may be necessary for thicker materials or critical applications to prevent cracking and ensure proper weld strength.
Stainless Steel Welding Electrodes
Stainless steel welding electrodes come in different types each with their own specific properties and characteristics. Some common types of stainless-steel welding electrodes are as follows.
1. E2209-16 – This electrode is used for welding duplex stainless steels (a combination of austenitic and ferritic stainless steels)
2. E2594-16 – This electrode is used for welding super duplex stainless steels (with even higher levels of corrosion resistance than duplex stainless steels).
3. E308/E308L – They are general-purpose stainless-steel electrodes. They are used for welding 304 and 304L stainless steel.
4. E309/E309L – The electrodes are designed for welding 309 and 309L stainless steel. They can also weld dissimilar metals such as carbon steel to stainless steel.
5. E316/E316L – These electrodes are used for welding 316 and 316L stainless steel, and other molybdenum-containing austenitic stainless steels.
Stainless Steel Welding Types
Some of the most common stainless steel welding methods are as follows.
1. Tungsten Inert Gas (TIG) Welding – TIG process uses a non-consumable tungsten electrode and an inert shielding gas to protect the weld from contamination. GTAW produces a high-quality, precise, and clean weld. This makes it suitable for thin materials and critical applications.
2. Metal Inert Gas (MIG) Welding – MIG process uses a consumable wire electrode and an inert shielding gas to protect the weld from contamination. GMAW is faster than GTAW welding. This makes MIG a suitable choice for thicker materials and faster welding speeds.
3. Flux-Cored Arc Welding (FCAW) – This process uses a flux-cored wire electrode and a shielding gas to protect the weld from contamination. FCAW is similar to MIG welding. But FCAW is more suitable for outdoor or windy conditions.
4. Resistance Spot Welding – This process uses electrical resistance to heat and joins the metal together. The most common use of spot welding is for joining thin sheets of stainless steel.
5. Plasma Arc Welding (PAW) – The PAW process uses a high-velocity plasma jet to heat and fuse the metal. PAW is similar to TIG welding. But PAW produces a deeper and more stable weld.
6. Laser Welding – LBW welding uses a high-powered laser beam to heat and fuse the metal. This welding type is suitable for thin materials and produces a precise and clean weld.
7. Electroslag Welding (ESW) – ESW process uses a consumable electrode and a slag pool to create the weld. The welding technique is suitable for thicker materials. It can produce high-quality and efficient welds.
TIG Welding Tips on Stainless Steel
Welders can master or make successful TIG welding on stainless steel by keeping in mind the following tips.
1. Selection of Filler Metal Appropriately – Before starting the welding process, make sure the diameter of the filler metal should be thinner than the base metal. This is because the thicker the rod or wire requires more heat to melt it. So, make sure the filler metal and base material should be compatible chemically. They should possess a similar mechanical property as well.
2. Taper Not more than 2.5 times the Electrode Diameter – The electrode geometry should be in balance. It means a taper should not be more than 2.5 times the electrode diameter. Further, it provides a focused arc capable of producing deep, thin beads and a narrow heat-affected zone. Contrary to it, if an electrode is with a taper of more than 2.5 times its diameter, then the arc may fan out. As a result, there is less penetration and a wider heat-affected zone.
3. Should be a Proper Fit up – This makes sure the use of only the required amount of filler metal. Without adding heat, it cannot be added filler metal.
4. Puddle Size – Weld puddles should be to the thickness of the base metal. In case, the puddle grows too large, welders should use foot pedals or fingertips to control/reduce heat input. Also, they can eliminate craters by easing down the current at the end of the weld or by adding a filler metal before the puddle solidifies.
5. Apply Suitable Size Electrode – There are many sizes available. But the common size of tungsten electrodes ranges from 3/32 to 1-1/4 of an inch. Always select the right size and it depends on variables like amperage, joint size, polarity, and thickness of base metal.
6. Balance of Travel Speed and Gas Flow – Welders should not move the torch too fast. Rather than keep flowing the gas at the puddle until the orange color fades.
7. Use Fingertip and Foot Control Properly – By doing so, both foot and hand are free to control of torch and amperage. There are different designs, so make sure you select the one that works best for you.
8. Using Pulsed Gas and Polarity – Welders should use pulsed gas tungsten arc welding (GTAW-P) with a direct current electrode negative current. The current alternates between a low background amperage and a high peak amperage in pulsing. The peak current imparts good penetration and fusion. And the background current maintains the arc and it allows the weld area to prevent cool, warping, and carbide precipitation.
Stainless Steel Welding Standards
Some of the most common standards are as follows.
1. American Welding Society (AWS) Standards – AWS D1.6/D1.6M Structural Welding Code – Stainless Steel (provides guidelines for welding stainless steel in structural applications).
2. American Society of Mechanical Engineers (ASME) Standards – ASME B31.3 Process Piping Code (provides guidelines for welding stainless steel piping in process applications).
3. International Organization for Standardization (ISO) Standards – ISO 14343 Welding Consumables – Wire Electrodes and Deposits for Gas Shielded Metal Arc Welding of Non-Alloy and Fine Grain Steels and the ISO 15614-1 Specification and Qualification of Welding Procedures for Metallic Materials – Welding Procedure Test.
4. European Welding Standards (EN) – EN ISO 15614-1 Specification and Qualification of Welding Procedures for Metallic Materials – Welding Procedure Test and EN ISO 3834 Quality Requirements for Fusion Welding of Metallic Materials.
5. ASTM International Standards – ASTM A312/A312M Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless-Steel Pipes and the ASTM A240 Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications.
Stainless Steel Welding School in the USA
Some schools that offer welding programs with a focus on stainless steel welding are as follows.
1. Lincoln Electric Welding School (Cleveland, OH) – It offers a variety of welding programs, including a stainless-steel welding program.
2. Tulsa Welding School (Tulsa, OK) – It offers a welding program that covers various welding processes, including stainless steel welding.
3. Hobart Institute of Welding Technology (Troy, OH) – It offers a comprehensive welding program that includes stainless steel welding.
4. Ohio Technical College (Cleveland, OH) – It offers a welding program that includes hands-on training in stainless steel welding.
5. Texas State Technical College (Waco, TX) – It offers a welding program that covers various welding processes, including stainless steel welding.
6. The Iron Workers and The Iron Workers Apprenticeship – It offers a comprehensive welding apprenticeship program that covers various welding processes, including stainless steel welding.
Individuals must research and compare programs to find the one that best fits their needs and career goals.
Stainless Steel Welding Certification
Some of the organizations that provide certification in stainless steel welding are-
1. American Welding Society (AWS) – AWS offers the Certified Welder (CW) and Certified Welding Inspector (CWI) programs. This includes an AWS certification exam that covers various welding processes, including stainless steel welding.
2. American Society of Mechanical Engineers (ASME) – ASME offers the Boiler and Pressure Vessel Code (BPVC) certification. This includes a certification exam for welding in high-pressure applications, including stainless steel welding.
3. International Organization for Standardization (ISO) – ISO offers certification for welders and welding procedures according to ISO 9606-1. This includes testing for welding stainless steel.
The certification exam typically includes a written test and a practical welding test. The certification is usually valid for a set period of time and may need to be renewed periodically.
Stainless Steel Welding Defects
Some of the most common welding defects are as follows.
1. Cracks – They are linear fractures in the weld metal due to improper welding technique, excessive heating or cooling, and welding of incompatible materials.
2. Porosity – This is the presence of small voids or holes within the weld metal due to gas pockets trapped in the weld pool.
3. Distortion – This is the deformation of the base metal due to heat input during welding.
4. Weld Spatter – They are unwanted metal particles that can be ejected from the weld during the process. They can cause surface defects and reduce the aesthetic appearance.
5. Incomplete Fusion – This occurs when the weld metal fails to fuse completely with the base metal. It leads to a weak joint that is susceptible to failure.
6. Undercut – This is a groove or depression in the base metal adjacent to the weld bead. Excessive heat input or improper welding technique causes this.
So, for avoiding welding defects, select the appropriate welding parameters, use proper stainless steel welding methods, and ensure proper preparation and cleaning of the weld joints.
Stainless Steel Welding Tips
Some tips for stainless steel welding are as follows.
1. Cleaning Weld Joint – For producing high-quality welds, proper cleaning of welds is a must. Make sure the joint is free of oil, dirt, rust, and other contaminants.
2. Controlling Heat Input – Stainless steel has a lower thermal conductivity than other metals. This makes it more susceptible to warping and distortion during the welding process. So, controlling the heat input can avoid overheating the material and causing distortion.
3. Consistent Welding Speed – Maintain a consistent welding speed to ensure consistent heat input and penetration. Slow and steady speed is often better than fast and uneven.
4. Appropriate Welding Technique – Selecting the appropriate welding technique depends on the type of joint being welded, the thickness of the base metal, and the welding process being used.
5. Use Correct Filler Metal – Must select a filler metal that is compatible with the base metal and the welding process being used. Some common filler metals for stainless steel welding include 308L, 309L, and 316L.
6. Weld Joint Proper Position – Welding joint’s proper position helps to ensure proper penetration and fusion. Position the joint correctly so that gravity helps hold the weld pool in place.
7. Post-Weld Cleaning/Finishing – Must clean the weld and surrounding area to remove any slag, spatter, or other debris. This will improve the appearance and durability of the finished product.
Stainless Steel Welding Safety
Some safety tips for stainless steel welding are as follows.
1. Fire Safety – Never weld near flammable materials or in areas where a fire could occur. Must keep a fire extinguisher nearby.
2. Hazardous Materials – Must store hazardous materials in a secure location. Follow proper handling procedures to prevent spills or accidents.
3. Inspect Equipment – Regularly inspect the welding equipment for defects. Repair or replace damaged components as needed.
4. Proper Grounding – To prevent electrical shock, properly ground the welding equipment.
5. Proper Training – All welders should receive proper training on handling hazardous materials and the safe operation of welding equipment.
6. Proper Ventilation – Adequate ventilation in the welding area is key to preventing inhalation of toxic fumes or gases. For this, use a fume extractor or ventilation system to remove welding fumes from the area.
7. Wear Safety Gear – Use personal protective equipment (PPE) such as an apron, welding helmet, and gloves. They protect against sparks, heat, and radiation.
Weldability of Stainless Steel
There are normally four types of stainless steel and their composition structures are as follows.
1. Austenitic Stainless Steel
A. Structures containing a few percent of ferrite (usual case)
- Excellent toughness and ductility
- Embrittlement can occur after long exposures between 550 and 900°C due to the decomposition of the ferrite to form the sigma phase
- Good resistance to intergranular corrosion for low carbon and stabilized grades
- Insensitive to hot cracking
B. Fully Austenitic Structures (exceptional)
- Excellent ductility and toughness
- Good resistance to intergranular corrosion for low carbon and stabilized grades
- It is sensitive to hot cracking during solidification
2. Ferritic Stainless Steel
A. Semi Ferritic Grades (0.04% C – 17% Cr)
- Poor ductility and toughness
- Post-weld heat treatment at about 800°C restores the mechanical properties and intergranular corrosion resistance
- Sensitive to embrittlement by grain coarsening above 1150°C
- Sensitive to intergranular corrosion
B. Ferritic Grades (0.02% C – 17-30% Cr)
- Generally insensitive to intergranular corrosion
- Satisfactory ductility and improved toughness compared to semi-ferritic grades
- Sensitive to embrittlement by grain coarsening above 1150°C
3. Austenitic – Ferritic Duplex Stainless Steel
- Excellent toughness and good ductility in the range from – 40% C to 275°C
- Insensitive to hot cracking
- Sensitive to embrittlement by sigma phase when exposed between 500 and 900°C
4. Martensitic Stainless Steel
- High tensile strength and hardness and good toughness, particularly for low carbon grades
- Sensitive to cold cracking, depending on the carbon and hydrogen contents and residual stress levels, below about 400°C
Stainless Steel Welding Employment Areas
The following industries provide stainless steel welding jobs.
- Aerospace Industry
- Automotive Industry
- Construction Industry
- Food and Beverage Industry
- Manufacturing Industry
- Oil and Gas Industry
Stainless Steel Welding Jobs
Some common types of stainless-steel welding jobs are as follows.
Stainless Steel Welding Salary
The experience, location, industry, and level of education or certification affect salary trends in the metal industry. Some general ranges for hourly and monthly salaries of stainless-steel welders are as follows.
Hourly Salary – Stainless steel welders in the United States can expect to earn an hourly wage ranging from around $15 to $35 per hour, with an average hourly wage of around $22 per hour.
Monthly Salary – The monthly salary for a stainless-steel welder in the United States can range from around $2,400 to $5,600 per month, with an average monthly salary of around $3,700 per month.
These figures are general estimates and can vary widely from place to place. Experienced stainless-steel welders with specialized skills and certifications may be eligible for higher salaries.
There are many stainless steel welding methods. Welding stainless steel is a critical process used in a variety of industries to join pieces of stainless steel. Welding involves the process of joining two or more pieces of stainless steel through the application of heat and pressure. For weld quality, select the appropriate welding method and other parameters. Safety is also a critical consideration for welders. With proper training, welders can develop valuable skills and pursue rewarding careers in this field. Also. welders must go through the user guide by manufacturers before starting to weld stainless steel.